Research Progress: 1. NMR investigation of the nucleic acid conformation. (a) Conformational properties of the furanose phosphate backbone in nucleic acids, as investigated by 13C NMR spectroscopy. (b) A theoretical study of the ring-current effect of the NMR of nucleic acids as evaluated using a graphical approach (collaborate with Giessner-Prettre and Pullman, Paris). (c) The observed and computed spectra of hydrogen-bonded NH resonances of Baker's Yeast tRNA. (d) The observed and computed spectra of methyl and methylene resonances of Baker's Yeast phenylalanine tRNA. (e) NMR studies on short deoxyoligonucleotide self-complementary duplexes. 2. Properties and function of oligonucleotide phosphotriesters. (a) Evaluation of electrostatic interaction in DNA by study of the duplex formation of a nonionic oligo(deoxythymidylate) analog (Tp(Et)7T) with poly(deoxyadenylate). (b) Effects of a trinucleotide ethyl phosphotriester, Gm over p (Et) Gm over p (Et)U on mammalian cells in culture. 3. Research on anti-viral substances with special emphasis on the mismatched analog of polyinosinic-polycytidylic duplex. (a) An integrated and comparative study of the antiviral effects and other biological properties of the poly I.poly C and its mismatched analogous. (b) Studies on the chronic effects and immunological features of an integrated and comparative study of the antiviral effects and other biological properties of the polyinosinic.polycytidylic acid duplex and its mismatched analogues.